cilley



,UNITED Srnrss PATENT OFFIGF..

GUSTAVUS B. MAYNADIER AND \VILLIAM H. GILLEY, OF BOSTON, MASS,

ATTRlTlON-MILL.

SPECIFICATION forming part of Letters Patent No. 292,170, dated January 22, 1884.

Application filed May 28, I883. (No modeLl To all whom it may concern.-

Be it known that we,'G. B. MAYNADIER and W. H. OILLEY,both of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Attrition-Mills, of which the following is a specification.

Our invention relates to improvements in attrition-mills in which one or more revolving recessed heads communicate with and are supplied from a rpceptacle or hopper, and in which the grindlng is effected by the attrition of the material within the heads against the material in the receptacle.

The object of our invention is to provide means for effectually carrying off the dust or flour as fast as it can be produced. To attain this object, our invention consists in the combination,with a perforated receptacle and the revolving recessed heads, of an air-chamber communicating with the interior of the rec-eptacle, and means for-forcing air into the chamber, as hereinafter fully set forth.

The best attrition-mills are those in which one portion of the material to be ground is contained in a recessed head and revolved against another portion of the material. In such mills the material is ground so rapidly that heretofore great difficulty has been experienced in carrying off the dust, and various expedients for effecting this have been adopted without accomplishing the desired result. By means of a force blast and our air-chamber attachment every particle of dust is removed and the material kept in the best condition for rapid grinding.

In the accompanying drawings, which illustrateour improvements as embodied in the best ways now known to us, Figure l'is a sectional view, and Fig. 2 a side view, of a mill having a fixed receptacle and two recessed revolving heads. Fig. 3 is a sectional view of a mill having a central receptacle adapted to revolve and to receive five recessed heads.

In Figs. 1 and 2, A is a fixed receptacle or hopper, to which the material to be ground is supplied through a spout, a, provided with.

two doors, a a opened alternately, so as to prevent the escape of dust. The recessed heads B communicate with the receptacle A,

and are supplied with material therefrom. These heads are revolved by any suitable mechanism, and .the attrition and impact of the material in them against that in the receptacle A rapidly reduces the material to dust, which must be extracted as rapidly as it is produced,

communicating with itsinterior through suitable perforations. The chambers b and a are connected air-tight by a packing, c of leather or the like, and the chamber a is also con nected with the hollow shafts b by means of tubes b Attached to and communicating with the chambersb are a series of deflectors, at, having their flaring mouths open in the direction in which the heads B revolve. By means of these deflectors the air is forcedinto the chambers b at a pressure due to the velocity with which these deflectors are carried by the rapidly-revolving heads. The air so forced in makes its way through the joints and perforations above mentioned, by which it is properly disseminated to thoroughly pervade the material and remove all dust, which it carries with it to an outlet leading preferably from the upper part of the receptacle A to bins for its collection. These bins are placed at different distances from the outlet, and thereby collect the dust in various grades of fineness, the coarsest falling into the bins nearest the outlet.

In Fig. 3 the central receptacle, A, is a hollow hub, and revolves, as well as the recessed heads B, and the whole is surrounded by an air-chamber, b, to which air is supplied by a pressure-blower or air-compressor of any suitable construction, through the main shaft 0 and the supporting-arms 0, made hollow for that purpose. The blast may be aided or en: tirely supplied by a worm or screw, 1), which is attached to the shaft of the lower recessed head. The shafts b of the heads B are also made hollow, and areconnected at their ends the pipes I) and the swivel-coupling I)". These hollow shafts I) admit air through the bottoms of the heads B directly to the places where the grinding is most rapid, and from which it has heretofore been found most (liffieult to properly remove it.

The joints between the heads and the central hub, A, and suitable perforations through the sides of the central hub, form communications between the air-chamber b and the interior of the central hub, A. and serve to disseminate the blast through the material to the best advantage for carrying the dust to the bins, as above stated.

In a previous application for a patent for improvement in grinding-mills is described a mill similar to the one shown in Figs. 1 and 2, with an additional recessed head in the bottom for stirring up and loosening the material, so as to afford a freer passage for the air-blast.

It will be apparent without further illustration or description that either of the above devices for applying a force blast may be applied to such a mill.

It is also obvious that the airchamber may be made to inclose the heads in Figs. 1 and 2 with an air-tight packing around the shafts of these heads, and be supplied with air under pressure by means of pipes connecting the airehambcrs with a pressure-blower or air-compressor, instead of by means of deflectors carried around by the heads.

We claim as our invention- In an attrition-mill, the combination, with a perforated receptacle or hopper and the revoluble recessed heads communicating with the receptacle, of an air-chamber communicating with the interior of the receptacle through the perforations and the joints around the heads, and means for forcing air into the air-chamber, substantially as and for the purpose set forth.

G. B. MAYNADIER. \V. H". CI'LLEY.

\Vitnesses:

L. N. MoLLER, J onx R. Snow. 

